[PATCH V5 3/4] cpu: Introduce getHost support for ARM CPU driver
Jiri Denemark
jdenemar at redhat.com
Fri May 15 09:51:43 UTC 2020
On Wed, May 13, 2020 at 18:48:34 +0800, Zhenyu Zheng wrote:
> Introduce getHost support for ARM CPU driver,
> read CPU vendor_id, part_id and flags from
> registers directly. These codes will only be
> compiled on aarch64 hardware.
>
> Signed-off-by: Zhenyu Zheng <zheng.zhenyu at outlook.com>
> ---
> src/cpu/cpu_arm.c | 162 ++++++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 162 insertions(+)
>
> diff --git a/src/cpu/cpu_arm.c b/src/cpu/cpu_arm.c
> index c7a6abfb22..6aef568503 100644
> --- a/src/cpu/cpu_arm.c
> +++ b/src/cpu/cpu_arm.c
> @@ -21,6 +21,10 @@
> */
>
> #include <config.h>
> +#if defined(__aarch64__)
> +# include <asm/hwcap.h>
> +# include <sys/auxv.h>
> +#endif
>
> #include "viralloc.h"
> #include "cpu.h"
> @@ -31,6 +35,13 @@
> #include "virxml.h"
>
> #define VIR_FROM_THIS VIR_FROM_CPU
> +#if defined(__aarch64__)
> +/* Shift bit mask for parsing cpu flags */
> +# define BIT_SHIFTS(n) (1UL << (n))
> +/* The current max number of cpu flags on ARM is 32 */
> +# define MAX_CPU_FLAGS 32
> +#endif
> +
>
> VIR_LOG_INIT("cpu.cpu_arm");
>
> @@ -486,11 +497,162 @@ virCPUarmValidateFeatures(virCPUDefPtr cpu)
> return 0;
> }
>
> +#if defined(__aarch64__)
> +/* Generate human readable flag list according to the order of */
> +/* AT_HWCAP bit map */
> +const char *aarch64_cpu_flags[MAX_CPU_FLAGS] = {
> + "fp", "asimd", "evtstrm", "aes", "pmull", "sha1", "sha2",
> + "crc32", "atomics", "fphp", "asimdhp", "cpuid", "asimdrdm",
> + "jscvt", "fcma", "lrcpc", "dcpop", "sha3", "sm3", "sm4",
> + "asimddp", "sha512", "sve", "asimdfhm", "dit", "uscat",
> + "ilrcpc", "flagm", "ssbs", "sb", "paca", "pacg"};
> +/**
> + * virCPUarmCpuDataFromRegs:
> + *
> + * @data: 64-bit arm CPU specific data
> + *
> + * Fetches CPU vendor_id and part_id from MIDR_EL1 register, parse CPU
> + * flags from AT_HWCAP. There are currently 32 valid flags on ARM arch
> + * represented by each bit.
> + */
> +static int
> +virCPUarmCpuDataFromRegs(virCPUarmData *data)
> +{
> + unsigned long cpuid;
> + unsigned long hwcaps;
> + VIR_AUTOSTRINGLIST features = NULL;
> + int cpu_feature_index = 0;
> + size_t i;
> +
> + if (!(getauxval(AT_HWCAP) & HWCAP_CPUID)) {
> + virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
> + _("CPUID registers unavailable"));
> + return -1;
> + }
> +
> + /* read the cpuid data from MIDR_EL1 register */
> + asm("mrs %0, MIDR_EL1" : "=r" (cpuid));
> + VIR_DEBUG("CPUID read from register: 0x%016lx", cpuid);
> +
> + /* parse the coresponding part_id bits */
> + data->pvr = (cpuid >> 4) & 0xfff;
> + /* parse the coresponding vendor_id bits */
> + data->vendor_id = (cpuid >> 24) & 0xff;
> +
> + hwcaps = getauxval(AT_HWCAP);
> + VIR_DEBUG("CPU flags read from register: 0x%016lx", hwcaps);
> +
> + features = g_new0(char *, MAX_CPU_FLAGS + 1);
> +
> + /* shift bit map mask to parse for CPU flags */
> + for (i = 0; i < MAX_CPU_FLAGS; i++) {
> + if (hwcaps & BIT_SHIFTS(i)) {
> + features[cpu_feature_index] = g_strdup(aarch64_cpu_flags[i]);
> + cpu_feature_index++;
> + }
> + }
> +
> + if (cpu_feature_index > 0) {
> + data->features = g_steal_pointer(&features);
> + data->nfeatures = cpu_feature_index;
There's no need for data->nfeatures as data->features is
NULL-terminated.
> + }
> +
> + return 0;
> +}
> +
> +static int
> +virCPUarmDecode(virCPUDefPtr cpu,
> + const virCPUarmData *cpuData,
> + virDomainCapsCPUModelsPtr models)
> +{
> + size_t i;
> + virCPUarmMapPtr map;
> + virCPUarmModelPtr model;
> + virCPUarmVendorPtr vendor = NULL;
> +
> + if (!cpuData || !(map = virCPUarmGetMap()))
> + return -1;
> +
> + if (!(model = virCPUarmModelFindByPVR(map, cpuData->pvr))) {
> + virReportError(VIR_ERR_OPERATION_FAILED,
> + _("Cannot find CPU model with PVR 0x%03lx"),
> + cpuData->pvr);
> + return -1;
> + }
> +
> + if (!virCPUModelIsAllowed(model->name, models)) {
> + virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
> + _("CPU model %s is not supported by hypervisor"),
> + model->name);
> + return -1;
> + }
> +
> + cpu->model = g_strdup(model->name);
> +
> + if (cpuData->vendor_id &&
> + !(vendor = virCPUarmVendorFindByID(map, cpuData->vendor_id))) {
> + virReportError(VIR_ERR_OPERATION_FAILED,
> + _("Cannot find CPU vendor with vendor id 0x%02lx"),
> + cpuData->vendor_id);
> + return -1;
> + }
> +
> + if (vendor)
> + cpu->vendor = g_strdup(vendor->name);
> +
> + if (cpuData->nfeatures) {
> + cpu->nfeatures = cpuData->nfeatures;
> + if (VIR_ALLOC_N(cpu->features, cpu->nfeatures) < 0)
> + goto error;
Even better (and without cpuData->nfeatures):
if (cpuData->features) {
cpu->nfeatures = virStringListLength((const char **)cpuData->features);
cpu->features = g_new0(virCPUFeatureDef, cpu->nfeatures);
> + for (i = 0; i < cpu->nfeatures; i++) {
> + cpu->features[i].policy = VIR_CPU_FEATURE_REQUIRE;
> + cpu->features[i].name = g_strdup(cpuData->features[i]);
> + }
> + }
> +
> + return 0;
> +
> + error:
> + for (i = 0; i < cpu->nfeatures; i++)
> + VIR_FREE(cpu->features[i].name);
> + VIR_FREE(cpu->features);
> + cpu->nfeatures = 0;
> + return -1;
The only way we could get here is when allocating cpu->features fails,
which means there's nothing to cleanup. Anyway, we can avoid the only
goto statement by using g_new0 and drop this section entirely.
> +}
> +
> +static int
> +virCPUarmGetHost(virCPUDefPtr cpu,
> + virDomainCapsCPUModelsPtr models)
> +{
> + virCPUDataPtr cpuData = NULL;
I forgot to mention this in my previous review, but this function would
benefit from using g_autoptr as we could just drop the cleanup section
and return directly in call cases:
g_autoptr(virCPUData) cpuData = NULL;
> + int ret = -1;
Not needed anymore.
> +
> + if (virCPUarmDriverInitialize() < 0)
> + goto cleanup;
return -1;
> +
> + if (!(cpuData = virCPUDataNew(archs[0])))
> + goto cleanup;
return -1;
> +
> + if (virCPUarmCpuDataFromRegs(&cpuData->data.arm) < 0)
> + goto cleanup;
return -1;
> +
> + ret = virCPUarmDecode(cpu, &cpuData->data.arm, models);
return virCPUarmDecode(cpu, &cpuData->data.arm, models);
> +
> + cleanup:
> + virCPUarmDataFree(cpuData);
> + return ret;
> +}
Not needed anymore.
> +#endif
> +
> +
> struct cpuArchDriver cpuDriverArm = {
> .name = "arm",
> .arch = archs,
> .narch = G_N_ELEMENTS(archs),
> .compare = virCPUarmCompare,
> +#if defined(__aarch64__)
> + .getHost = virCPUarmGetHost,
> +#endif
> .decode = NULL,
> .encode = NULL,
> .dataFree = virCPUarmDataFree,
Jirka
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